category: Health

Take a Cold Shower!

The benefits of a cold shower, while largely anecdotal, are recommended for everything from hangovers to excessive libidos. Despite its reputation as a quasi-folk remedy, recent research suggests exposure to cold water may help treat depression, anxiety and even attention-deficit disorders. The invigorating effects of cold water are apparent to all of us who have accidentally opened the cold tap in the shower or purposefully jumped into a swimming pool. The shock of cold water on our skin generates an active and near immediate response from our sympathetic nervous system, the activity of which is regulated in the brain through the release of signaling molecules called neurotransmitters. Norepinephrine is the primary neurotransmitter responsible for the sympathetic “fight or flight” responses we experience during times of stress, panic and anger. The activity of the sympathetic nervous system can also be elicited by environmental stressors, like exposure to cold temperatures. Norepinephrine is synthesized primarily in the locus coeruleus, a part of the brainstem in constant communication with most of the brain.

Researchers at Charles University in Prague have shown that when volunteers were immersed in cold water (14°C), there was a five-fold increase in plasma noradrenaline/norepinephrine levels, as compared to baseline. An increase in noradrenaline concentration of that magnitude suggests it was triggered by the sympathetic nervous system. Based on this observation, it is reasonable to assume that an individual exposed to cold stressors should display not just physiological, but also behavioral signs of sympathetic nervous system activation. Assessing the degree to which these changes differ between individuals may allow us to determine whether if, and to what extent, the noradrenergic system is dysfunctional.

Studies of rats exposed to cold temperatures have demonstrated that there are changes in the rate at which neurons in the locus coeruleus adapt to an injection of electrical current. These changes imply that cold-exposure was effective in modifying the self-regulatory capabilities and sensitivity of norepinephrine producing cells in that region of the brain. The relevant significance of these findings is in that they support the idea that exposure to cold stressors can affect cellular changes in the locus coeruleus, and likely by extension, the behavior of the organism itself. It would be interesting to fully determine whether the effects of prolonged and acute exposure to cold stressors are maintained for an extended duration.

The biologist Dr. Nikolai Shevchuk, contends that the origin of noradrenergic dysfunction in humans can be attributed to individual genetic susceptibility and a more general evolutionary mismatch between our modern and ancestral environments. He believes that cold-water exposure can be adapted as a therapy for depression and other conditions that may have their roots in noradrenergic dysfunction. Dr. Shevchuk believes that modern humans lack sufficient “thermal exercise” of the locus coeruleus, and that this was not a problem faced by our ancestors.

Cost-effective methods of indoor climate control have only been developed within the last century and any behavioral symptoms rooted in a lack of “thermal exercise” would clearly be exacerbated by climate-controlled lifestyles. It would be interesting to determine whether diagnoses of anxiety disorder or other conditions predicted by noradrenergic dysfunction have increased following the introduction of affordable climate control systems in the mid-to late 20th century. We live in a time where climate-controlled conditions are common, and it is clear that we are living in conditions much different from that of our ancestors. Whether this evolutionary incongruity is responsible for the prevalence of anxiety and depressive disorders has yet to be determined, but the findings presented here suggest that cold temperatures can potentially treat depression and anxiety in humans.

References

Šrámek, P., Šimečková, M., Janský, L., Šavlíková, J., & Vybíral, S. (2000). Human physiological responses to immersion into water of different temperatures, European Journal of Applied Physiology, 81, 436-442.

Shevchuk, N. A. (2008). Adapted cold shower as a potential treatment for depression, Medical Hypotheses, 70, 995-1001.

Stanford, S. C. (1995). Central noradrenergic neurones and stress. Pharmac. Ther., 68(2), 297-342.

Jedema, H. P., Finlay, J. M., Sved, A. F., & Grace, A. A. (2001). Chronic cold exposure potentiates crh-evoked increases in electophysiologic activity of locus coeruleus neurons. Society of Biological Psychiatry, 49, 351-359.

Jedema, H. P., & Grace, A. A. (2003). Chronic exposure to cold stress alters electrophysiological properties of locus coeruleus neurons recorded in vitro. Neuropsychopharmacology, 28, 63-72.

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